Gannat is a commune in the Allier department in central France. Gannat was a sub-prefecture until 1926, with a population of around 5,800 in…Gannat is a commune in the Allier department in central France. Gannat was a sub-prefecture until 1926, with a population of around 5,800 inhabitants. There is a castle, two churches of which one is partly Romanesque with a 9th-century Gospel Book. The Cultures du Monde Festival is held every July. The patron saint of Gannat is Saint Procule.